The declining Ogallala Aquifer beneath
the Southern High Plains may necessitate dryland crop production and cotton (Gossypium
hirsutum L.) is a well-adapted and potentially profitable alternative
crop. The limited growing season duration of the Texas Panhandle and
southwestern Kansas, however, imposes significant production risk due to
incomplete boll maturation. Emphasizing earlier boll production that is usually
confined to sites on lower fruiting branches may reduce risk, but offsetting
high planting densities are needed to maintain desirable lint yield. In this
study, the authors aimed to quantify planting: 1) row width and 2) in-row
spacing effects on growth, yield, and fiber quality of dryland cotton.
The authors carried
out a field experiment and a crop growth simulation. The field tests of row
widths from 0.25 to 0.76 m and plant densities with in-row spacing ranging from
0.075 to 0.15 m were conducted from 1999 to 2005 on a nearly level Pullman clay
loam (fine, mixed, superactive, thermic Torrertic Paleustoll) managed in a
wheat (Triticum aestivum L.), cotton, fallow (W-Ctn-F) rotation. And
to expand the basis of comparison, cotton growth and yields were simulated
using GOSSYM and long-term (1958-2000) weather records from Bushland, TX, as
input for all combinations of 0.38 or 0.76 m row widths and plant spacing of
0.075, 0.10 and 0.15 m.
Experimental and
computer simulated plant height and harvested boll number increased
significantly with increased row spacing and, occasionally, in-row plant
spacing. Modeled lint yield for 0.38 m rows decreased by approximately 50%
compared with the 582 kg·ha-1 yield for conventional row
spacing, which was practically duplicated by field observations in 2001 and
2004. Measured fiber quality occasionally improved with conventional row
spacing over ultra-narrow rows, but was unaffected by plant spacing.
In conclusion, using
narrow rows or frequent plant spacing did not improve net lint yield or fiber
quality of dryland cotton. Then, concentrating on early set cotton boll
production by adapting planting geometry to increase plant population and
consequently cotton yield is not recommended under dryland conditions to
overcome a thermally limited growing season.
Article by R.
L. Baumhardt, et al, from USA.
Full access: http://mrw.so/4krGKW
Image by andrewkt263, from Flickr-cc.
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